Three Mountain West states, three variations on the same machine, and the differences are exactly the details that decide what a repair notice costs you.
Montana: lien or lawsuit, the city picks
MCA 7-14-4122(1): "The city or town council has power to regulate and provide for the construction or repair of sidewalks, foot pavements, curbs, gutters, or any combination thereof." The timeframe for compliance is set by each city's ordinance, not by the state. If you do not comply and the city contracts the work, subsection (2) gives the city two collection routes: "The amount so paid is a lien upon the lot and may be enforced or the amount may be recovered against the owner by a suit before any court of competent jurisdiction."
That "or" matters. Most states stop at the lien; Montana lets the city sue you personally instead. Either way, the deadline that binds you is in the local ordinance, so that ordinance is the first document to request.
Wyoming: the 30-day do-it-yourself window
W.S. 15-6-501 and 15-6-502 (first-class cities, 4,000+ population) run sidewalk construction as a contracted improvement program with a built-in escape hatch: after the ordinance and a notice served "not less than thirty (30) days before the date for hearing objections," owners get "a period of thirty (30) days during which parties so desiring may construct the walk abutting their property." Build it yourself inside the window, to spec, and the city contractor never touches your frontage. Miss it, and the contractor must finish "within sixty (60) days after he is so notified," with "the total cost of all sidewalks constructed by the city contractor... assessed... as a special assessment against the property in front of which the sidewalk is built," notice and grading costs included.
Wyoming's 30-day self-build window ties Illinois and Indiana in our deadline league table, but it is a friendlier kind of clock: theirs counts down to the city doing the work, Wyoming's counts down your option to do it cheaper.
Idaho: "dangerous and unsafe," then 30 days to pay
Idaho Code 50-316: "Cities may provide by general ordinance for the construction, repair or removal of sidewalks which are deemed by the council to be dangerous and unsafe, and for the replacing thereof, assess the cost as provided in section 50-1008 to the property in front of which the same shall be constructed, repaired or laid." A parallel section, 50-317, covers clearing: "Cities are empowered to cause all sidewalks and alleys to be cleared of snow, ice and rubbish... and to assess the cost thereof against the private property so cleared."
The collection mechanism, 50-1008, has the state's one hard number: assessments "if not paid within thirty (30) days after mailing of notification of assessment, shall be declared delinquent and be certified to the tax collector of the county," collected like other city taxes. One genuine oddity: unlike Montana, North Dakota, or Alabama, Idaho's text never calls the charge a lien. It rides the tax rolls instead, which changes how it clouds a title and how it gets contested. Our verified Boise record shows the state's biggest city running its own version day to day.
What to do
- Montana: get the ordinance, then decide fast. The state statute has no deadline; the city's does. And because the city can sue you personally instead of just liening the lot, ignoring the notice has sharper downside than usual.
- Wyoming: use the 30 days. The self-build window exists precisely so owners can beat the contractor's price. Get a quote the week the notice arrives.
- Idaho: dispute "dangerous and unsafe" early, pay within 30 late. The council's dangerousness finding is the trigger; question it before the work happens. Once assessed, the 30-day payment window is what keeps the charge off the county tax rolls.
Sources: MCA 7-14-4122 (official Montana Code Annotated site, quoted verbatim), W.S. 15-6-501 and 15-6-502 (via Justia's code archive, disclosed per our methodology), and Idaho Code 50-316, 50-317, and 50-1008 (official Idaho Legislature site, quoted verbatim). City rules live in the complete city guide.